Apparatus for counting bacterial colonies



April 10, 1951 F. w. KAVANAGH APPARATUS FOR COUNTING BACTERIAL COLONIES Filed May 19, 1949 M 0 0 T N Z V A MW m D W F ITTOANEVS Patented Apr. 10, 1951 APPARATUS FOR COUNTING BACTERIAL COLONIES Frederick W. Kavanagh, New York, N. Y.

Application May 19, 1949, Serial No. 94,219

2 Claims. 1

This invention relates to a method of and apparatus for counting that is useful for example for the counting of bacterial colonies as well as for other purposes.

One object of the invention is a new and improved counting device wherein the operator is relieved of mental processes attendant with noting the objects counted as well as the number of the count, thereby reducing error and materially increasing the speed with which the count can be made.

Another object of the invention is to provide a new and improved method for counting objects or things to eliminate the human error encountered in mental processes, and at the same time indicate which objects or things have been counted.

Another object of the invention is a new and improved counting device for counting bacterial colonies characterized by its simplicity, accuracy and low cost of manufacture and which eliminates substantially all human errors in the counting process.

Another object of the invention is a new and improved counting device.

The above and other objects of the invention will become more apparent in the following description and accompanying drawings which illustrate certain embodiments of the invention.

In the drawings:

Fig. 1 is a perspective view of one of the embodiments of the invention;

Fig. 2 is a cross-sectional view of the marking vdevice illustrated in the embodiment shown in the most frequently repeated operations in bacterial laboratories of hospitals, public health agencies, colleges, and in many industries. In the present methods, with which I am familiar, the counting of such colonies is tedious and exacting work.

I have found that with certain methods of counting even a slight distraction of the person making the count, which frequently runs into hundreds and sometimes even thousands, usually means that he loses either his place on the dish or the mental sum of the count made, and must start over. Even without such distraction, t -e errors encountered with present methods of counting are frequent, since the operator must mentally note the particular colonies which have been counted, as well as the number of such colonies.

With my invention, I am able to relieve the operator of the mental tasks of making a sum of the counts as well as noting the particular colonies counted, and have found that by so doing, the results are considerably more accurate than would otherwise be obtained, and that the results can be obtained far more rapidly.

Briefly, the invention as illustrated includes a suitable marking device and means responsive to the marking device for registering the number of marks made by it. Although I have illustrated in my embodiment of the invention a conventional fountain pen as the marking means, because of the facility with which bacterial colonies can be indicated or marked on a glass surface by merely pressing the pen point slightly on the surface to leave a dot of ink, it is apparent that other types of marking implements or devices (such as pencils, wax pencils, or other stylii) may be used, depending on the character of the surface to be marked by the device.

Associated with the marking device is a suitable counting means which may be either electric or mechanical, and which is adapted to respond to a slight movement of the marking device during a marking operation, to actuate a tallying or counting means to tally the total number of marks made by the device.

In Figs. 1, 2 and 3 I have illustrated one embodiment of my invention, and for the purposes of this application I have illustrated it in connection with the counting of bacterial colonies.

In Fig. l, a glass petri dish I0 is shown in an inverted position so that the bottom of the dish can be used for the purpose of placing indicating marks in the form of a small drop of ink over each bacteria1 colony. These indicating marks are denoted by the numeral 12. The marking means H1 in this embodiment is electrically connected by a suitable cable or lead it to a counter [8 adapted to respond to the pressure exerted on the marking device it as each mark is made on the back of the petri dish I0. With thi device, therefore, the operator merely needs to place a mark on the petri dish over each of'the bacterial colonies scattered throughout the layer of agar in the dish, and by so doing a tally is automatically made of the total number of such marks, and at the same time an indication is made of the particular colonies which have been counted. Thus, any distraction on the part of the operator will not cause the count or the operators place on the dish to be lost.

More particularly, the marking device comprises an outer cylindrical housing 26 having a amasvs opposing lugs 30 which cooperate with corre-- sponding slots 32 in the front end of the body or housing 20. in the upper or closed end of the slots 32 by means of a collar 34 threadedly fastened to 'the housing 20, with the inner end 36 loosely contacting the. front side of the pen retaining collar 24. In this way, the application of pressure against the: pen point 38 of the pen 22 inthe direction of the arrowa will cause. the pentp move from a position shown by thesolid linesin Fig, 2 to, a dotted line position also illustrated in Fig. 2.

The other end of the housing 28 is enclosed by a suitable cap 48 slidably engaging the housing andheld in position thereon by means of a small screw 42 (Fig. 1). This cap 44 carries the pair of contacts 44 and 46 individually mounted in the cap 40 by means of a block of insulating material 48 held within the cap to by the screw 42 which passes through the housing and cap walls and threadedly engages the opening 42 in the block of insulating material 48. Contact 44 is supported on the end of a simple flat spring member 50, while contact 45 is supported in cooperative relationship with contact 44 by spring member 52 which extends beyond the contact 46 and engages the back end of the fountain pen housing 22., The spring 52 i also provided with apair of lugmembers 54 curved to conform to the fountain pen body so that the end thereof will nest in and be retained by the spring 52. The tension on this spring isv adjusted so that it will yield under pressure on the point 38 to effect closure of the contacts 44 and 46, and upon release a of the pressure will act to return the fountainpen from the dotted line position to the solid line position, as shown in Fig. 2. The cable or lead I 6 is preferably of a two-conductor type and each conductor is connected to one of said contact like numerals have been used to designateglike components. This circuit includes a transformer 62 having, a;pri mary 64 connected inserieswith the switch 58 to a suitable source of alternating current. The secondary E6 of the transformer 62 is-connected in series with the magnetic counting device 56 and in series with the contacts 44 and 46 described in connection with Fig.2, so that whenthe contacts are closed, the circuit through the coil 56 and the secondary 66 will be completed to actuate the count. A condenser 68 is preferably connected in parallel with. the contacts to reduce arcing and to increase the life of the contactsr It. is apparent from the above that with: this invention substantially all human error i elimi-' nated in the counting of bacterial colonies, andI have found that the count can be made far. more rapidly than with conventional methods with which I am familiar.

Moreover, the device is, simple in structure and will respond quickly and accurately to the mark- These lugs 30 are loosely retained.

ing operation to tally the number of marks so made.

Furthermore, with my new and improved device, theoperator canpause frequently in the middle of a count to rest his eyes, or even encounter numerous distractions, Without the necessity, of a complete recounting of the colonies. Furthermore, plates having thousands of colonies .can be counted whereas with prior methods the counting ofcolonies on such plates would not be attempted, and the complete experiment may have to be repeated. It is apparent, therefore, thatnotonly can the count be accomplished more rapidly by my method and apparatus, but con- .siderable time and money is saved in avoidingthe repetition of experiments should thecolonies be more numerous than anticipated.

What is claimed is:

l. A device for counting bacterial colonies scattered throughout a layer of transparent material in a shallow-dish, comprising an elongated cylindrical housing having a pair of opposed slots formed inwardly from one end thereof, a fountain pen having a pair of oppositelydisposed and outwardly extending lugs secured to said pen at a point spaced from-the point thereof, said pen being loosely retained within the housing with the lugs cooperating with said slots, acollar removably fastened to the slotted end of said-hous ing to retain the lugs in engagement with the slots, spring means insulatingly mounted in the other end-of said housingand engaging the inner end of said fountain pen, a contact mounted on said spring means, a fixed contact insulatingly mounted in cooperation, with the first, saidcontact, said contacts being adapted to open and close in response to pivotal movement of the fountain pen within the housing produced by the application of pressure to the point of said pen, and-also being adapted to be connected to an electromagnetic counter responsive to the actuation of said contacts.

2. A counting device for counting bacterial colonies, comprising fountain pen means for marking the colonies, as they are counted, a housing for said pen including a pair of opposing slots, a collar fastened to said pen and having apair of oppositely disposed outwardly extending lugs for cooperation with the slots in said housing, removable means on said housing for retaining said lugs within the slots, a pair of contacts mounted within said housing and adapted to be actuated upon movement of the pen relative to the housing and about the lugs as each colony is marked, said contacts being adapted to be connected to an electromagnetic counter that is responsive to their actuation to register the number of colonies marked.

FREDERICK W. KAVANAGH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 646,541 Jenkins et al Apr. 3,.1900

FOREIGN PATENTS Number Country Date 44,974 Switzerland Oct. 2, 1908 45,650 Switzerland Sept. 24, 1908 86,580 Switzerland Feb. 16, 1921 116,826 Germany Jan. 21, 1901 141,812 Germany June 23, 1903 

